Needle attachment for sound-reproducing machines.



' F. W. CLAYBROOK.

NEEDLE ATTACHMENT FOR SOUND REPRODUCING MACHINES.

APPLICATION FILED JAN. 31. I911- msmss, Patented Oct. 8, 1918..

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FREDERICK W. CLAYBBOOK, OF BALTIMORE, MARYLAND.

NEEDLE ATTACHMENT FOR SOUND-REPBODUCING MACHINES..

Specification of Letters Patent.

Patented Get. 8, 1918.

Application filed January 31, 1917. Serial No. 145,652.

To all whom it may concern:

Be it known that I, FREDERICK W. CLAY- BROOK, a citizen of the United States, residing at Baltimore, in the State of Maryland, have invented certain new and useful Improvements in Needle Attachments for Sound-Reproducing Machines, of which the following is a specification.

This invention relates to attachments for holding the needle in sound reproducing machines with the object of absorbing the undesirable vibrations due to various causes and which result in harsh grating or screeching sounds; and also of reducing the wear on the record disk to a minimum.

As is well known, the channels in the record disk which are produced by the action of the needle in the sound recorder are undulating and vary in depth and steepness with the amplitude and pitch of the sound waves projected upon the diaphragm of the recorder. The needle of the graphophone, phonograph or other reproducing machine following in these grooves or channels, is caused to vibrate in exact unison with the undulations, except for certain undesirable variations hereinafter referred to, and this generally speaking, reproduces the same sounds in the horn or other sound transmitter.

Among the causes which contribute to undesirable sounds which interfere with the transmission of the true sound waves may be mentioned the following: l/Vhen the undulations in the record channel are formed of gradual curves the needle follows faithfully all of the indentations, but if a very sudden or steep incline is encountered, the needle will be thereby thrown upward with greater rapidity or violence and may be caused to actually leave the record, immediately returning upon the rebound and not only producing a false tone or sound but to a certain extent marring the record, many repetitions of this action resulting in wear and injury.

In order to accurately reproduce the sounds or notes corresponding to the record, the vibrations of the needle must be caused solely by the recorded undulations. Like all bodies that are free to vibrate, the needle has a certain rate of vibrations of its own to which it will respond if that particular note or number of vibrations is impressed upon it. From this it follows that if perchance the needle encounters a certain number of undulations in the record to which it is attuned, or with which its natural vibrations are in synchronism, it will add its own vibrations thus produced to those caused by the record, thereby multiplying the amplitude of vibrations of the needle and produc mg a false note which is recognized as a screeching sound occasionally produced.

Undesirable sounds, such as the harsh grating sounds, are produced by the imporfections in old or worn-out records- Foreign substances, such as particles of dust, encountered by the needle also produce false and undue vibrations which result in improper sounds.

Certain of the causes above mentioned have been heretofore known and various attempts have been made to overcome the defects. Thus it has been proposed to surround the needle with a rubber sleeve and to interpose a rubber disk or block or a spiral spring between the needle and the soundbox in the endeavor to absorb undue vibrations; and also to remove the dust particles from the record by means of a separate brush holder clamped to the shank of the usual needle holder or to the casing of the sound-box. Instead of analyzing the deficiencies of such prior devices it is deemed suflicient to hereinafter point out the re.- quirements and the manner in which I have embodied them in the device disclosed herein.

In the accompanying drawings, Figure 1 is a side elevation of the usual sound box and needle holder of a. phonograph together with a sectional view of a device embodying the features of my invention; Fig. 2 is a top plan view of my device; and Fig. 3 is an end view of the same showing the attachment of the brush.

In the drawings, I have shown conventionally the outer end 2 of the tone-arm, having pivoted thereto the sound-box tube 3, carrying the reproducerv or sound-box 4 which is provided with usual diaphragm 6, to which is attached the arm 7, connected to the plate 8, carrying the needle-socket 10.

My needle-carrying attachment for absorbing false vibrations and accurately transmitting the true vibrations corresponding with the undulations in the record comprises a' main supporting member 15 which may be constructed of brass or other suitable material, and is provided at one end with a socket having a contour corresponding to the end of the netalle-socket l0, and through which pro eets the supporting pm 17. riveted or otherwise rigidly attached thereto, this pin being inserted into the being made fast by the rivets 24 and 25.

The needle 30, is received in a hole passing through the member 23 and may be ad justedtherein as desired to vary the strength of tone, and then secured by the set screw 31. In case the upper end of the needle projects it is prevented from ever contacting with the metal of the member 15 by the felt strip 19 attached to the lower side.

The parts are so arranged that the needle aperture in the lower member 23 has the same angle of inclination as the needle socket in the member 10. Thisis necessary because it is essential that the predetermined proper angle which the needle makes With the record disk 35 shall remain unaltered.

It is necessar that the vibrations of the needle shall be 111 the vertical plane passing through the needle 30 and the pin 17, and for this reason I provide a fiat or leaf spring which is rigidly clamped at its ends in the members 15 and 23, and is of suflicient width to resist any sidewise or any lateral torsional or tilting movements. The needle is, therefore, compelled to vibrate in a vertical plane, and the device as an entirety transmits the thrusts imparted by the undulatory record path in alinement with the arm 7.

While the leaf spring 20 is sufficiently stiff to serve as a rigid connecting portion between the members 23 and 15, as regards all legitimate undulations in the record disk, yet it is sufficiently resilient to absorb unusual vibrations caused, bythe imperfections of worn records, and the tendency to a sudden and unnatural increase in the amplitude of vibrations caused by a tendency to rebound from a very steeply inclined nndulation, or an overtone or harmonic due to record undulations producing vibrations in synchronism or attuned to the natural note of vibration of the needle itself. These superinduced vibrations are definitely ab sorbed by the molecular structure of the metal leaf spring surrounded by the deadening envelop of felt, so that substantially nothing but the fundamental or true record vibration is transmitted by the attachment as an entity to the arm 7 of the sound-box. These characteristics of my device due to the rigid yet resilient leaf spring connector 20, are not true of devices which relay upon an other foreign substance engaging the needle.

It has been proposed to provide a separate attachment carrying abrush. To efliciently perform its function it should be adjacent the needle but should not interfere with the functioning of the shock-absorbing medium.

I therefore provide a transverse slot in-the. leading end of the member 15. into which is inserted the back 27 carrying the brush portion 28. Inasmuch as it is necessary to renew the brush occasionally I prefer to make the back 27 and slot Wedge-shaped, the parts fitting tightly yet permitting the brush to be detached.

I have described in detail the construction illustrated in the accompanying drawing for a claims and Without departing from my invention. I have specified certain materials for the different parts but other materials may be employed which produce the same result in substantially the same manner.

I claim:

1. A holder for sound needles, comprising a supporting member and a needle clamping member, a connector having its ends secured respectively to said members, said connector comprising a spring plate resilient in the vertical plane of the needle but non-resilient in a plane transverse thereto, and cushioning media inter- 1posed between the connector and said memers.

2. A holder for sound reproducing needles, comprising a supporting member having a pin adaptedto enter the needlesocket of a sound reproducing machine, a leaf spring secured to said member atone end to yield in the vertical plane of said pin, a needle clampin member carried by the opposite end of said spring and having a needle socket having the same angle of inclination as said pin, and cushioning reproducing i memes media interposed. between the ends of the sprin and said members.

3. i holder for sound reproducing needles, comprising a supporting member having means for attachment to the needle socket of a sound reproducing machine at one end thereof and brushing means at the opposite er d, aneedle clampinmember having a socket to receive e'nee le and a 10 spring plate connecting said members which needl 4. A holder for sound plane of said reproducing needles as set forth in claim 3, wherein said brushing means is supporting member.

detachably secured to said 15 testimony whereof I aiiix my signature. Y

FREDERICK W. CLAYBROOK. 

